1. Field of the Invention
The present invention relates to a substrate processing apparatus and a method of manufacturing a semiconductor device, which are adapted to manufacture a semiconductor device by performing processes such as a thin film forming process, an oxidation process, an impurity diffusion process, an annealing process, a chemical vapor deposition (CVD) process, and an etching process on a substrate such as a silicon wafer.
2. Description of the Prior Art
As a substrate processing apparatus, there is a batch type substrate processing apparatus capable of processing a predetermined number of substrates at a time. In a batch type substrate processing apparatus, a desired process is performed by charging a predetermined number of substrates in a substrate holder, loading the substrate holder into a process furnace, and introducing process gas into the process furnace in a state where the substrates are heated.
An exemplary batch type substrate processing apparatus is disclosed in Patent Document 1.
The substrate holder (boat) is placed on a furnace port cover (seal cap) that is used for air-tightly closing a furnace port. By lifting the seal cap using a lift unit (boat elevator), the boat can be loaded into the process furnace. During a process, the boat is rotated by a boat rotary mechanism so that process quality can be uniformly maintained.
In the process furnace, the boat is simply supported only by the seal cap. Therefore, if a transversal force is applied to the boat due to, for example, an earthquake, the boat may fall down. Particularly, if the boat falls down during a loading or unloading work or when the boat is placed outside the process furnace, the falling of the boat becomes a significant accident by which the operation time of the substrate processing apparatus is largely affected: for example, the substrate processing apparatus cannot be operated for a long time.
For this reason, in another substrate processing apparatus, a boat is mechanically shackled on a seal cap for preventing falling of the boat. In the case of a process furnace of such a substrate processing apparatus, a mechanically strong metallic material is used for making a boat fixing part and a boat fixing unit. The fixing part and fixing unit are configured to be loaded into the process furnace together with a boat.
In a substrate processing process such as a film forming process, for example, if a corrosive gas (e.g., chlorine (Cl)-containing gas) is used or etching is performed by using a corrosive gas, the fixing part and the fixing unit may be corroded, and thus substrates may be contaminated.
In the related art, a metallic part is covered with a quartz member so as not expose the metallic part directly to the inside of a furnace. However, eventually, metal corrosion occurs due to corrosive gas permeated through a narrow gap.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 06-168904.